Active vs. Passive Residual Volume in FRC and deep freediving

[sanso]

Hey freediving thinkers.

I've put together some thoughts on lung volumes, namely active and passive residual volumes, that have been part of our courses for years, but hadn't been put in proper writing before.

I know this is helping our students understand their deep dives better, especially with regards to risks of lung and trachea barotrauma, so I hope your training will benefit from this.

Please let me know what you think.

https://wefreedive.com/blog/56-active-vs-passive-residual-volume-in-freediving

 

[cdavis]

Very nicely done! The combination of the RV/a and RV/p concept and Walters analysis go a long way toward illuminating what is happening during a deep dive (or not so deep if you dive FRC). This is needed info in the freediving world. Walter is absolutely right that a previous squeeze reduces the depth at which you can get squeezed ( personal experience).

Question for you, Sanso.

I dive FRC, have a depth induced threshold(very closely related to RV/p) of 80-100 ft, dive with a completely relaxed chest(harder than it sounds), equalize with a combination of BTV switching to Frenzel near the bottom. For me, Frenzel acts like reverse packing, pulling up air from my lungs using the muscles in my throat and tongue(see my thread "Frenzel =reverse packing??"). It takes focus to avoid using chest muscles in this process. I stop decending either when I can not equalize further or can feel that I'm getting near squeeze. I have not figured out how to do mouthfil.

Provided my chest is really completely relaxed, how would mouthfil help me? It seems like my depth adaptation depth is only reduced by the amt of air in my cheeks. Is it possible to relax farther than I already am if I use mouthfil?

Connor

 

[sanso]

Oooh, interesting and more complex than this topic. I'll have to take some time for a meaningful reply.

Off to work now.

 

[cdavis]

thanks sanso.

Going to work?? Oh yeah, I forget that Thialand is 12 hours off my local time.